Calcium sulphate/hydroxyapatite composite periodontal cement dressing loaded with doxycycline for localised drug delivery: Mechanical, radiographical, and antimicrobial insights

This study developed and evaluated calcium sulphate/hydroxyapatite (CS/HAp)-based periodontal cement dressings incorporating doxycycline (DOX) as a localized drug delivery system. Characterisation via SEM, FTIR, XRD, and radiographic imaging revealed that while the manufacturing process and powder packing yielded relatively uniform total porosities across all formulations (~26–42% surface; ~30–36% bulk), composition strongly dictated the material's performance. Radiopacity progressively increased with higher HAp content due to greater X-ray attenuation from calcium-rich phases. Mechanical testing demonstrated that the mixed-phase compositions significantly enhanced load-bearing capacity compared to single-component materials. Specifically, the S 1.5 H 0.5 formulation exhibited the highest break force, indicating superior load-bearing capacity, driven by the chemical cementing effect of calcium sulphate reacting with potassium sulphate, whilst displaying a ductile, elastic–plastic deformation behaviour via progressive pore collapse. The composites exhibited gradual in vitro degradation behaviour, excellent radiopacity, drug release profile characterized by a relatively rapid initial release followed by a slower and more gradual release phase, while inhibiting Staphylococcus aureus and Escherichia coli in vitro . Among the formulations, the S 1.5 H 0.5 composition demonstrated the optimum balance of mechanical properties, structural uniformity, and drug release behaviour, highlighting its strong potential for clinical dental and periodontal applications.